(CNN) -- Mount Redoubt volcano in southern Alaska erupted four times on Friday, shooting ash as high as 51,000 feet, scientists said.

A series of eruptions has been rattling Alaska's Mount Redoubt volcano since Sunday.

The latest eruption took place at 8:30 p.m. (12:30 a.m. Saturday ET), according to the National Weather Service. That eruption followed three other ones earlier Friday.

The eruptions are the latest in a series that began Sunday.

The Alaska Volcano Observatory said the alert level remains at its highest possible designation -- red -- indicating that an eruption is under way or imminent and that the eruption will produce a "significant emission of volcanic ash into the atmosphere."

The weather service said the ash is drifting north and northeast. However, only "very light" amounts are expected to fall Friday in the Anchorage area, about 100 miles east-northeast of the volcano.

Alaska Airlines limited flights to and from Anchorage on Friday, according to the airline's Web site. It canceled all its Thursday flights to and from Anchorage after an eruption earlier in the day sent an ash cloud 65,000 feet high.